Validation of write data subsequent to destaging to auxiliary storage for completion of peer to peer remote copy

ABSTRACT

A primary storage controller receives a write command from a host, to write data that is to be controlled by the primary storage controller. The data is written to local storage of the primary storage controller and subsequently the data is destaged from the local storage of the primary storage controller to store the data in an auxiliary storage of the primary storage controller. The data is transmitted to a secondary storage controller for writing the data to local storage of the secondary storage controller and for subsequently destaging the data from the local storage of the secondary storage controller to store the data in an auxiliary storage of the secondary storage controller. The data stored in the auxiliary storage of the primary storage controller is compared to the data stored in the auxiliary storage of the secondary storage controller to determine whether the write command is successfully executed.

BACKGROUND 1. Field

Embodiments relate to the validation of write data subsequent to thedestaging of the write data to auxiliary storage for completion of peerto peer remote copy.

2. Background

A storage controller may control access to storage for one or more hostcomputational devices that may be coupled to the storage controller overa network. A storage management application that executes in the storagecontroller may manage a plurality of storage devices, such as diskdrives, tape drives, flash drives, direct access storage devices (DASD),etc., that are coupled to the storage controller. A host may sendInput/Output (I/O) commands to the storage controller and the storagecontroller may execute the I/O commands to read data from the storagedevices or write data to the storage devices.

In certain storage systems, a primary storage controller that providesI/O access to storage volumes may be coupled to a secondary storagecontroller. The secondary storage controller may store backup copies ofstorage volumes of the primary storage controller. The storage volumesof the primary storage controller are referred to as primary storagevolumes and the backup copies of storage volumes are referred to assecondary storage volumes.

The secondary storage volumes may be generated either synchronously orasynchronously by copying primary storage volumes from the primarystorage controller to the secondary storage controller, and this processmay be referred to as a peer to peer remote copy (PPRC). SynchronousPPRC causes each write to a primary storage volume to be performed tothe secondary storage volume as well, and the I/O (i.e., the write) isconsidered to be complete when writes to both the primary storage volumeand the secondary storage volume have completed. In asynchronous PPRC,an I/O is considered to be complete when updates have been made to theprimary storage volume, and the primary storage volume is copied to thesecondary storage volume when time permits.

SUMMARY OF THE PREFERRED EMBODIMENTS

Provided are a method, system, and computer program product in which aprimary storage controller receives a write command from a host, towrite data that is to be controlled by the primary storage controller.The data is written to a local storage of the primary storage controllerand subsequently the data is destaged from the local storage of theprimary storage controller to store the data in an auxiliary storage ofthe primary storage controller. The data is transmitted to a secondarystorage controller for writing the data to a local storage of thesecondary storage controller and for subsequently destaging the datafrom the local storage of the secondary storage controller to store thedata in an auxiliary storage of the secondary storage controller. Thedata stored in the auxiliary storage of the primary storage controlleris compared to the data stored in the auxiliary storage of the secondarystorage controller to determine whether the write command issuccessfully executed.

In additional embodiments, in response to determining that the datastored in the auxiliary storage of the primary storage controller isidentical to the data stored in the auxiliary storage of the secondarystorage controller, an indication is sent to the host that the writecommand is successfully executed.

In further embodiments, in response to determining that the data storedin the auxiliary storage of the primary storage controller is notidentical to the data stored in the auxiliary storage of the secondarystorage controller, performing at least one of the following: retryingexecution of the write command; and sending an indication to the hostthat the write command is not successfully executed.

In certain embodiments, the write command is for writing the data to aprimary storage volume of the primary storage controller that is to bemaintained in a secure peer to peer remote copy relationship with asecondary storage volume of the secondary storage controller, wherein tomaintain the secure peer to peer remote copy relationship the primarystorage volume and the secondary storage volume are both destaged toauxiliary storages and validated as storing identical data.

In further embodiments, the comparing is performed, in response to anindication included in the write command to perform the comparing.

In yet further embodiments, in response to determining that there is noindication included in the write command to perform the comparing, thewrite command is denoted as being successfully executed to the hostwithout waiting for the data to be destaged to the auxiliary storage ofthe primary storage controller and to the auxiliary storage of thesecondary storage controller.

In additional embodiments, the comparing of the data stored in theauxiliary storage of the primary storage controller to the auxiliarystorage of the secondary storage controller to determine whether thewrite command is successfully executed is performed at predeterminedintervals of time or after every predetermined number of writes.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 illustrates a block diagram of a computing environment comprisinga primary storage controller coupled to a secondary storage controller,in accordance with certain embodiments;

FIG. 2 illustrates a flowchart that shows how a peer to peer remote copy(PPRC) of storage volumes is established in a normal mode in thecomputing environment, in accordance with certain embodiments;

FIG. 3 illustrates a flowchart that shows circumstances in whichsecondary storage volumes cannot be used instead of primary storagevolumes in the normal mode of peer to peer remote copy operations, inaccordance with certain embodiments;

FIG. 4 illustrates a modified I/O command for secure peer to peer remotecopy operations, in accordance with certain embodiments;

FIG. 5 illustrates a first flowchart that shows validation of write datasubsequent to the destaging of the write data to auxiliary storage forcompletion of peer to peer remote copy, in accordance with certainembodiments;

FIG. 6 illustrates a second flowchart that shows validation of writedata subsequent to the destaging of the write data to auxiliary storagefor completion of peer to peer remote copy, in accordance with certainembodiments;

FIG. 7 illustrates a block diagram that shows conditions under which thedetermining of whether the primary storage volume the secondary storagevolume have identical data is performed while secure PPRC is inprogress, in accordance with certain embodiments;

FIG. 8 illustrates a block diagram of a cloud computing environment, inaccordance with certain embodiments;

FIG. 9 illustrates a block diagram of further details of the cloudcomputing environment of FIG. 8, in accordance with certain embodiments;and

FIG. 10 illustrates a block diagram of a computational system that showscertain elements that may be included in the storage controllers and/orthe host(s), as described in FIGS. 1-9, in accordance with certainembodiments.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings which form a part hereof and which illustrate severalembodiments. It is understood that other embodiments may be utilized andstructural and operational changes may be made.

Certain embodiments allow a write I/O operation on a primary storagevolume of primary storage controller to complete after the write datacorresponding to the write I/O has been copied to a secondary storagevolume of a secondary storage controller and after the write data hasbeen destaged to auxiliary storage of the primary storage controller andthe secondary storage controller, after determining that the primarystorage volume stored in the auxiliary storage of a primary storagecontroller is identical to the secondary storage volume stored inauxiliary storage of a secondary storage controller, where the primarystorage volume and the secondary storage volume are in a peer to peerremote copy relationship. The comparison of the primary storage volumeto the secondary storage volume is performed while the peer to peerremote copy operations are in progress.

In certain embodiments, the comparison of the primary storage volume tothe secondary storage volume is performed, in response to an indicationincluded in the I/O command (e.g., write command) to perform thecomparing. In additional embodiments, the comparing of the data storedin the auxiliary storage of the primary storage controller to the datastored in the auxiliary storage of the secondary storage controller todetermine whether the write command is successfully executed isperformed at predetermined intervals of time or after everypredetermined number of writes.

Exemplary Embodiments

FIG. 1 illustrates a block diagram of a computing environment 100comprising a primary storage controller 102 that is coupled to asecondary storage controller 104. The primary storage controller 102receives I/O requests from one or more hosts 106, and responds to theI/O requests by performing read or write operations with respect toprimary storage volumes 108. The primary storage volumes 108 are logicalstorage volumes corresponding to physical storage volumes that storedata in auxiliary storage 110 comprising a plurality of storage devices112, 114, where the auxiliary storage 110 is coupled to the primarystorage controller 102.

The I/O requests received by the primary storage controller 102 from thehosts 106 may comprise an I/O command for peer to peer remote copy in asecure mode or an I/O command for peer to peer remote copy in a normalmode (as shown via reference numeral 115).

The primary storage controller 102, the secondary storage controller104, and the hosts 106 may comprise any suitable computational deviceincluding those presently known in the art, such as, a personalcomputer, a workstation, a server, a mainframe, a hand held computer, apalm top computer, a telephony device, a network appliance, a bladecomputer, a processing device, a controller, etc. The plurality ofstorage controllers 102, 104 may provide redundancy because if theprimary storage controller 102 undergoes a failure from which recoveryis not possible, the secondary storage controller 104 may be configuredto communicate with the hosts 106 and the secondary storage controller104 may perform the functions of the primary storage controller 102 thatfailed. Additionally, in case of loss of data in the primary storagevolumes 108 of the primary storage controller 102, the lost data may berecovered from the secondary storage volumes 116 that are in a peer topeer remote copy relationship 118 with the primary storage volumes 108.

The primary storage controller 102, the secondary storage controller104, and the hosts 106 may be elements in any suitable network, such as,a storage area network, a wide area network, the Internet, an intranet,etc. In certain embodiments, the primary storage controller 102, thesecondary storage controller 104, and the hosts 106 may be elements in acloud computing environment.

A storage management application 120 that executes in the primarystorage controller 102 interfaces with a storage management application122 that executes in the secondary storage controller 104 to establishthe peer to peer remote copy relationship 118 between the primarystorage volumes 108 and the secondary storage volumes 116. The storagemanagement application 120 may also perform staging of data (shown viareference numeral 124) from the auxiliary storage 110 of the primarystorage controller 102 to the local storage 126 of the primary storagecontroller 102. Similarly, the storage management application 122 mayperform staging of data (shown via reference numeral 128) from theauxiliary storage 132 of the secondary storage controller 104 to thelocal storage 130 of the secondary storage controller 104, where theauxiliary storage 132 of the secondary storage controller 104 iscomprised of a plurality of storage devices 134, 136. The staging ofdata may comprise movement of data.

The storage management application 120 may also perform destaging ofdata (shown via reference numeral 124) from the local storage 126 of theprimary storage controller 102 to the auxiliary storage 110 of theprimary storage controller 102. Similarly, the storage managementapplication 122 may perform destaging of data (shown via referencenumeral 128) from the local storage 130 of the secondary storagecontroller 104 to the auxiliary storage 132 of the secondary storagecontroller 104. The destaging of data may comprise movement of data.

The local storage 126, 130 may be comprised of a volatile and/or anon-volatile storage. For example, in certain embodiments the localstorage 126, 130 may be comprised of dynamic random access memory (DRAM)and/or solid state memory. The auxiliary storage 110, 132 have a muchlarger amount of storage capacity in comparison to the local storage126, 130, and the auxiliary storage 110, 132 may be comprised of harddisks or other storage devices. When peer to peer remote copy operationsare performed in a normal mode then a host application that executes inthe host 106 may be made aware that an I/O operation is complete, oncedata has successfully been written to the local storage 126 even thoughit has not been destaged to the auxiliary storage 110. At an opportunetime, data may be destaged from the local storage 126 to the auxiliarystorage 110, to free up space in the local storage 126. Typically, thelocal storage 126 is coupled via a bus to the processor of the primarystorage controller 102 and is accessed much faster in comparison to theauxiliary storage 110 that may be external to an enclosure of theprimary storage controller 102, and the local storage 130 of thesecondary storage controller 104 is designed in a similar manner.

The primary storage controller 102 also includes a secure peer to peerremote copy application 138, where in certain embodiments the securepeer to peer remote copy application 138 allows a write I/O operationfrom a host 106 to a primary storage volume 108 of the primary storagecontroller 108 to complete after the write data corresponding to thewrite I/O has been copied to a secondary storage volume 116 of thesecondary storage controller 104 and after the write data has beendestaged to auxiliary storage 110 of the primary storage controller 108and auxiliary storage 132 of the secondary storage controller 104, afterdetermining that the primary storage volume 108 contents stored in theauxiliary storage 110 of the primary storage controller 102 is identicalto the secondary storage volume 116 contents stored in the auxiliarystorage 122 of the secondary storage controller 104, where the primarystorage volume 108 and the secondary storage volume 116 are in a securepeer to peer remote copy relationship 118. The comparison of the primarystorage volume to the secondary storage volume is performed while thepeer to peer remote copy operations are in progress in a secure mode.

In certain embodiments, the secure peer to peer remote copy application138 and the storage management applications 120, 122 may be implementedin software, firmware, hardware or any combination thereof.

FIG. 2 illustrates a flowchart 200 that shows how a peer to peer remotecopy (PPRC) of storage volumes is established in a normal mode in thecomputing environment 100, in accordance with certain embodiments.

Control starts at block 202 in which primary storage volumes 108 aremaintained in a normal mode PPRC relationship 118 to secondary storagevolumes 116. A write operation for writing to a primary storage volume108 is received (at block 204) at the primary storage controller 102from a host 106. The primary storage controller 102 writes (at block206) the data corresponding to the write operation in the local storage126 of the primary storage controller 102. Then if the normal mode PPRCrelationship is a synchronous PPRC relationship (reference numeral 208)control proceeds to block 212 in which the data is copied from the localstorage 126 of the primary storage controller 102 to the local storage130 of the secondary storage controller 104, and the primary storagecontroller 102 then indicates (at block 214) to the host 106 that thewrite operation is complete.

From block 206 control proceeds to block 216 if the normal mode PPRCrelationship 118 is an asynchronous PPRC relationship 210. At block 216,the primary storage controller 102 indicates to the host 106 that thewrite operation is complete, and the data is copied (at block 218) fromthe local storage 126 of the primary storage controller 102 to the localstorage 130 of the secondary storage controller 104.

From blocks 214 and 218 control proceeds to blocks 220 and 222. In block220, data is destaged from the local storage 126 of the primary storagecontroller 102 to the auxiliary storage 110 of the primary storagecontroller 102, and in block 222 data is destaged from the local storage130 of the secondary storage controller 104 to the auxiliary storage 132of the secondary storage controller 104.

Therefore, FIG. 2 illustrates certain embodiments in which in normalmode PPRC, an I/O operation may be indicated to the host 106 as beingcomplete, even though the auxiliary storage has not been updated (viadestaging from local storage) with the write corresponding to the I/Ooperation.

FIG. 3 illustrates a flowchart 300 that shows circumstances in whichsecondary storage volumes 116 cannot be used instead of primary storagevolumes 108 in the normal mode of peer to peer remote copy operations,in accordance with certain embodiments.

Control starts in parallel in block 302 and block 304, where in block302 a determination is made that there is an error in a secondarystorage controller 104 (e.g., secondary storage controller 104 is notoperating properly), and in block 304 a detection is made of an error inthe auxiliary storage 132 of the secondary storage controller 104.

From blocks 302, 304 control proceeds to block 306 in which it isdetermined that erroneous data for secondary storage volume 116 isstored in the auxiliary storage 132 of the secondary storage controller104. Control proceeds in parallel to blocks 308 and 310. In block 308 afailover of the primary storage controller 102 to the secondary storagecontroller 104 occurs. In block 310, the primary storage controller 102requests the secondary storage controller 104 for data from thesecondary storage volume 116, in response to loss of data in the primarystorage volume 108.

Control proceeds from blocks 308 and 310 to block 312, in which it isdetermined that data from the secondary storage volume 116 cannot beused to replace data stored in the primary storage volume 108.Therefore, when a failover needs to be done or when there is a loss ofdata in the primary storage controller 102, then at this critical stagethe data in the secondary storage volume 116 cannot be used to replacethe data stored in the primary storage volume 108. In certainembodiments, by providing a secure mode of peer to peer remote copyoperations, mechanisms are provided to detect an error in a PPRCrelationship between the primary storage volume 108 and the secondarystorage volume 116 well in advance of the time at which data insecondary storage volume 116 is needed to replace the data stored in theprimary storage volume 108. For write data that is designated atcritical data (e.g., name and telephone number of customers) by a user,the secure mode of PPRC is performed, rather than the normal mode ofPPRC.

FIG. 4 illustrates a modified I/O command 400 (a write command in thisexample) for secure peer to peer remote copy operations, in accordancewith certain embodiments. The modified I/O command 400 has one or morefields allocated for write operation indications that include storagevolumes and/or addresses to which data is to be written (shown viareference numeral 402). One or more fields of the modified I/O command400 includes the data to be written (shown via reference numeral 404).In contrast to normal I/O commands, the modified I/O command 400 has afield that indicates whether a secure peer to peer remote copy is to beperformed (shown via reference numeral 406). The secure peer to peerremote copy indication 406 may be provided via a number of differentmechanisms, including by indicating that the write data is critical dataor by providing indications to compare data stored in auxiliary storage110 of the primary storage controller 102 and auxiliary storage 132 ofthe secondary storage controller 104, prior to indicating to the host106 than the modified I/O command 400 has been successfully completed.

FIG. 5 illustrates a first flowchart 500 that shows validation of writedata subsequent to the destaging of the write data to auxiliary storagefor completion of peer to peer remote copy, in accordance with certainembodiments. In FIG. 5 the operations of the primary storage controller(reference numeral 504) are shown to the left of the dashed line 502,and the operations of the secondary storage controller (referencenumeral 506) are shown to the right of the dashed line 502.

Control starts at block 508 in which a primary storage volume 108 ismaintained in a secure PPRC relationship 118 to a secondary storagevolume 116. Control proceeds to block 510 in which the primary storagecontroller 102 receives a write command to write data from a host 106.The primary storage controller 102 writes the data to local storage 126of the primary storage controller 102 and transmits (at block 512) thedata to the secondary storage controller 104.

From block 512 control proceeds to block 514 in which the primarystorage controller 102 destages the data from the local storage 126 ofthe primary storage controller 102 to the auxiliary storage 110 of theprimary storage controller 102. Subsequently, at block 516, the primarystorage controller 102 stages the data from the auxiliary storage 110 ofthe primary storage controller 102 to the local storage 126 of theprimary storage controller 102.

From block 512 control also proceeds to block 520 in which the secondarystorage controller 104 writes the data to the local storage 130 of thesecondary storage controller 104. The secondary storage controller 104destages (at block 521) the data from the local storage 130 of thesecondary storage controller 104 to the auxiliary storage 132 of thesecondary storage controller 104. The secondary storage controller 104then stages (at block 522) the data from the auxiliary storage 132 ofthe secondary storage controller 104 to the local storage 130 of thesecondary storage controller 104 and transmits the data to the primarystorage controller 102.

From block 516 and 522 control proceeds to block 518 in which theprimary storage controller 102 determines if the staged data to thelocal storage 126 of the primary storage controller 102 is identical tothe data received from the secondary storage controller 104 (i.e., theprimary storage controller 102 compares data written in auxiliarystorage 110 of primary storage controller 102 and data written inauxiliary storage 132 of secondary storage controller 104).

If at block 518, the primary storage controller 102 determines that thedata written in auxiliary storage 110 of the primary storage controller102 is different from the data written to the auxiliary storage 132 ofthe secondary storage controller 104 (“No” branch 524) then controlproceeds to block 526 in which the secure PPRC relationship between theprimary storage volume 108 to which the data is written and thesecondary storage volume 116 to which the data is copied is suspendeduntil the error is resolved. The error may have been caused by a varietyof reasons including those shown earlier in FIG. 2.

If at block 518, the primary storage controller 102 determines that thedata written in the auxiliary storage 110 of the primary storagecontroller 102 is identical to the data written to the auxiliary storage132 of the secondary storage controller 104 (“Yes” branch 528) thencontrol proceeds to block 530 in which the primary storage controller102 sends an indication to the host 106 that the write command has beensuccessfully performed, and the secure PPRC relationship 118 issuccessfully maintained.

FIG. 6 illustrates a second flowchart 600 that shows validation of writedata subsequent to the destaging of the write data to auxiliary storagefor completion of peer to peer remote copy, in accordance with certainembodiments.

A primary storage controller 102 receives (at block 602) a write commandfrom a host 106, to write data that is to be controlled by the primarystorage controller 102. The data is written to a local storage 126 ofthe primary storage controller 102 and subsequently the data is destagedfrom the local storage 126 of the primary storage controller 102 tostore the data in an auxiliary storage 110 of the primary storagecontroller 102 (at block 604). The data is transmitted (at block 606) toa secondary storage controller 104 for writing the data to a localstorage 130 of the secondary storage controller 104 and for subsequentlydestaging the data from the local storage 130 of the secondary storagecontroller 104 to store the data in an auxiliary storage 132 of thesecondary storage controller 104.

From block 606 control proceeds to block 608 in which the data stored inthe auxiliary storage 110 of the primary storage controller 102 iscompared to the data stored in the auxiliary storage 132 of thesecondary storage controller 104 to determine whether the write commandis successfully executed.

From block 608 control proceeds in parallel to block 610 and 612. Inblock 610, in response to determining that the data stored in theauxiliary storage 110 of the primary storage controller 102 is identicalto the data stored in the auxiliary storage 132 of the secondary storagecontroller 104, an indication is sent to the host 106 that the writecommand is successfully executed. In block 612, in response todetermining that the data stored in the auxiliary storage 110 of theprimary storage controller 102 is not identical to the data stored inthe auxiliary storage 132 of the secondary storage controller 104, theprimary storage controller 102 performs at least one of the following:retrying execution of the write command; and sending an indication tothe host 106 that the write command is not successfully executed.

FIG. 7 illustrates a block diagram 700 that shows conditions under whichthe determining of whether the primary storage volume 108 and thesecondary storage volume 116 have identical data is performed whilesecure PPRC is in progress, in accordance with certain embodiments.

In certain embodiments, the comparing to determine whether the primarystorage volume 108 and the secondary storage volume 116 have identicaldata is performed for critical data (shown via reference numeral 702),where the critical data (i.e., data which is more important than therest of the data and should be protected more securely than the rest ofthe data) may be designated by a user. In certain embodiments, someusers may request is that they want their important transactions to beguaranteed on both the primary storage controller 102 and the secondarystorage controller 104, and in such embodiments the data read fromauxiliary storage on both the primary storage controller 102 and thesecondary storage controller 104 are verified to be identical beforetransactions are deemed to be complete. In certain embodiments,important transactions may be transactions over a predetermined monetaryamount (e.g., $10,000).

In additional embodiments, the comparing of the data stored in theauxiliary storage 110 of the primary storage controller 102 to theauxiliary storage 132 of the secondary storage controller 104 todetermine whether the write command is successfully executed isperformed at predetermined intervals of time (shown at block 704) orafter every predetermined number of writes (shown at block 706). Forexample, the determination of whether the write command is successfullyexecuted may be performed every 12 hours or every N writes, where anexemplary value of N may be 1000.

Therefore, FIGS. 1-7 illustrate certain embodiments in which a securepeer to peer remote copy relationship 118 is maintained between primarystorage volumes 108 of a primary storage controller 102 and secondarystorage volumes 116 of a secondary storage controller 104.

Cloud Computing Environment

Cloud computing is a model for enabling convenient, on-demand networkaccess to a shared pool of configurable computing resources (e.g.,networks, servers, storage, applications, and services) that can berapidly provisioned and released with minimal management effort orservice provider interaction.

Referring now to FIG. 8, an illustrative cloud computing environment 50is depicted. As shown, cloud computing environment 50 comprises one ormore cloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 8 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 9, a set of functional abstraction layers providedby cloud computing environment 50 (FIG. 8) is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 9 are intended to be illustrative only and embodiments of theinvention are not limited thereto.

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include mainframes, in oneexample IBM zSeries* systems; RISC (Reduced Instruction Set Computer)architecture based servers, in one example IBM pSeries* systems; IBMxSeries* systems; IBM BladeCenter* systems; storage devices; networksand networking components. Examples of software components includenetwork application server software, in one example IBM WebSphere*application server software; and database software, in one example IBMDB2* database software. * IBM, zSeries, pSeries, xSeries, BladeCenter,WebSphere, and DB2 are trademarks of International Business MachinesCorporation registered in many jurisdictions worldwide.

Virtualization layer 62 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers;virtual storage; virtual networks, including virtual private networks;virtual applications and operating systems; and virtual clients.

In one example, management layer 64 may provide the functions describedbelow. Resource provisioning provides dynamic procurement of computingresources and other resources that are utilized to perform tasks withinthe cloud computing environment. Metering and Pricing provide costtracking as resources are utilized within the cloud computingenvironment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal provides access to the cloud computing environment forconsumers and system administrators. Service level management providescloud computing resource allocation and management such that requiredservice levels are met. Service Level Agreement (SLA) planning andfulfillment provide pre-arrangement for, and procurement of, cloudcomputing resources for which a future requirement is anticipated inaccordance with an SLA.

Workloads layer 66 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation; software development and lifecycle management; virtualclassroom education delivery; data analytics processing; transactionprocessing; and secure PPRC processing 68 as shown in FIGS. 1-8.

Additional Embodiment Details

The described operations may be implemented as a method, apparatus orcomputer program product using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. Accordingly, aspects of the embodiments may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,aspects of the embodiments may take the form of a computer programproduct. The computer program product may include a computer readablestorage medium (or media) having computer readable program instructionsthereon for causing a processor to carry out aspects of the presentembodiments.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present embodiments may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present embodiments.

Aspects of the present embodiments are described herein with referenceto flowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instruction.

FIG. 10 illustrates a block diagram that shows certain elements that maybe included in the primary storage controller 102, the secondary storagecontroller 104, the hosts 106, or other computational devices inaccordance with certain embodiments. The system 1000 may include acircuitry 1002 that may in certain embodiments include at least aprocessor 1004. The system 1000 may also include a memory 1006 (e.g., avolatile memory device), and storage 1008. The storage 1008 may includea non-volatile memory device (e.g., EEPROM, ROM, PROM, flash, firmware,programmable logic, etc.), magnetic disk drive, optical disk drive, tapedrive, etc. The storage 1008 may comprise an internal storage device, anattached storage device and/or a network accessible storage device. Thesystem 1000 may include a program logic 1010 including code 1012 thatmay be loaded into the memory 1006 and executed by the processor 1004 orcircuitry 1002. In certain embodiments, the program logic 1010 includingcode 1012 may be stored in the storage 1008. In certain otherembodiments, the program logic 1010 may be implemented in the circuitry1002. One or more of the components in the system 1000 may communicatevia a bus or via other coupling or connection 1014. Therefore, whileFIG. 10 shows the program logic 1010 separately from the other elements,the program logic 1010 may be implemented in the memory 1006 and/or thecircuitry 1002.

Certain embodiments may be directed to a method for deploying computinginstruction by a person or automated processing integratingcomputer-readable code into a computing system, wherein the code incombination with the computing system is enabled to perform theoperations of the described embodiments.

The terms “an embodiment”, “embodiment”, “embodiments”, “theembodiment”, “the embodiments”, “one or more embodiments”, “someembodiments”, and “one embodiment” mean “one or more (but not all)embodiments of the present invention(s)” unless expressly specifiedotherwise.

The terms “including”, “comprising”, “having” and variations thereofmean “including but not limited to”, unless expressly specifiedotherwise.

The enumerated listing of items does not imply that any or all of theitems are mutually exclusive, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expresslyspecified otherwise.

Devices that are in communication with each other need not be incontinuous communication with each other, unless expressly specifiedotherwise. In addition, devices that are in communication with eachother may communicate directly or indirectly through one or moreintermediaries.

A description of an embodiment with several components in communicationwith each other does not imply that all such components are required. Onthe contrary a variety of optional components are described toillustrate the wide variety of possible embodiments of the presentinvention.

Further, although process steps, method steps, algorithms or the likemay be described in a sequential order, such processes, methods andalgorithms may be configured to work in alternate orders. In otherwords, any sequence or order of steps that may be described does notnecessarily indicate a requirement that the steps be performed in thatorder. The steps of processes described herein may be performed in anyorder practical. Further, some steps may be performed simultaneously.

When a single device or article is described herein, it will be readilyapparent that more than one device/article (whether or not theycooperate) may be used in place of a single device/article. Similarly,where more than one device or article is described herein (whether ornot they cooperate), it will be readily apparent that a singledevice/article may be used in place of the more than one device orarticle or a different number of devices/articles may be used instead ofthe shown number of devices or programs. The functionality and/or thefeatures of a device may be alternatively embodied by one or more otherdevices which are not explicitly described as having suchfunctionality/features. Thus, other embodiments of the present inventionneed not include the device itself.

At least certain operations that may have been illustrated in thefigures show certain events occurring in a certain order. In alternativeembodiments, certain operations may be performed in a different order,modified or removed. Moreover, steps may be added to the above describedlogic and still conform to the described embodiments. Further,operations described herein may occur sequentially or certain operationsmay be processed in parallel. Yet further, operations may be performedby a single processing unit or by distributed processing units.

The foregoing description of various embodiments of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many embodiments of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims hereinafter appended.

What is claimed is:
 1. A method, comprising: receiving, by a primarystorage controller, a transaction to perform a write command from ahost, to write data that is to be controlled by the primary storagecontroller; in response to determining that a user has requested thatsecure peer to peer remote copy operations are to be performed betweenthe primary storage controller and a secondary storage controller,performing secure peer to peer remote copy operations comprising:writing the data to a local storage of the primary storage controllerand subsequently destaging the data from the local storage of theprimary storage controller to store the data in an auxiliary storage ofthe primary storage controller; transmitting the data to the secondarystorage controller for writing the data to a local storage of thesecondary storage controller and subsequently destaging the data fromthe local storage of the secondary storage controller to store the datain an auxiliary storage of the secondary storage controller; subsequentto the destaging of the data from the local storage of the primarystorage controller to the auxiliary storage of the primary storagecontroller, staging the data from the auxiliary storage of the primarystorage controller to the local storage of the primary storagecontroller; subsequent to the destaging of the data from the localstorage of the secondary storage controller to the auxiliary storage ofthe secondary storage controller, staging the data from the auxiliarystorage of the secondary storage controller to the local storage of thesecondary storage controller, and then transmitting the data staged tothe local storage of the secondary storage controller to the primarystorage controller; and subsequent to the staging of the data to thelocal storage of the primary storage controller and the transmitting ofthe data staged to the local storage of the secondary storage controllerto the primary storage controller, comparing the data staged to thelocal storage of the primary storage controller to the data received atthe primary storage controller from the secondary storage controller todetermine whether the write command is successfully executed; and inresponse to determining that the user has requested that normal peer topeer remote copy operations are to be performed between the primarystorage controller and the secondary storage controller, performing apeer to peer remote copy of the data from the primary storage controllerto the secondary storage controller, wherein in the peer to peer remotecopy an indication is provided to the host that the write command issuccessfully executed without comparing the data stored in the auxiliarystorage of the primary storage controller to the data stored in theauxiliary storage of the secondary storage controller to determinewhether the write command is successfully executed as in the secure peerto peer remote copy operations.
 2. The method of claim 1, wherein theperforming further comprises: in response to determining that the datastaged to the local storage of the primary storage controller isidentical to the data received from the secondary storage controller,sending an indication to the host that the write command is successfullyexecuted.
 3. The method of claim 1, wherein the comparing of the datastored in the auxiliary storage of the primary storage controller to theauxiliary storage of the secondary storage controller to determinewhether the write command is successfully executed is performed atpredetermined intervals of time.
 4. The method of claim 1, wherein: thelocal storage of the primary storage controller is coupled via a bus ofthe primary storage controller to a processor of the primary storagecontroller, and the auxiliary storage of the primary storage controlleris external to an enclosure of the primary storage controller; and thelocal storage of the secondary storage controller is coupled via a busof the secondary storage controller to a processor of the secondarystorage controller and the auxiliary storage of the secondary storagecontroller is external to an enclosure of the secondary storagecontroller.
 5. The method of claim 1, wherein in the normal peer remotecopy operations, in response to an erroneous copy of the data beingstored in the auxiliary storage of the secondary storage controller, thecopy of the data stored in the secondary storage controller cannot beused to correctly replace the data stored in the primary storagecontroller.
 6. A system, comprising: a memory; and a processor coupledto the memory, wherein the processor performs operations, the operationsperformed by the processor comprising: receiving, by a primary storagecontroller, a transaction to perform a write command from a host, towrite data that is to be controlled by the primary storage controller;in response to determining that a user has requested that secure peer topeer remote copy operations are to be performed between the primarystorage controller and a secondary storage controller, performing securepeer to peer remote copy operations comprising: writing the data to alocal storage of the primary storage controller and subsequentlydestaging the data from the local storage of the primary storagecontroller to store the data in an auxiliary storage of the primarystorage controller; transmitting the data to the secondary storagecontroller for writing the data to a local storage of the secondarystorage controller and subsequently destaging the data from the localstorage of the secondary storage controller to store the data in anauxiliary storage of the secondary storage controller; subsequent to thedestaging of the data from the local storage of the primary storagecontroller to the auxiliary storage of the primary storage controller,staging the data from the auxiliary storage of the primary storagecontroller to the local storage of the primary storage controller;subsequent to the destaging of the data from the local storage of thesecondary storage controller to the auxiliary storage of the secondarystorage controller, staging the data from the auxiliary storage of thesecondary storage controller to the local storage of the secondarystorage controller, and then transmitting the data staged to the localstorage of the secondary storage controller to the primary storagecontroller; and subsequent to the staging of the data to the localstorage of the primary storage controller and the transmitting of thedata staged to the local storage of the secondary storage controller tothe primary storage controller, comparing the data staged to the localstorage of the primary storage controller to the data received at theprimary storage controller from the secondary storage controller todetermine whether the write command is successfully executed; and inresponse to determining that the user has requested that normal peer topeer remote copy operations are to be performed between the primarystorage controller and the secondary storage controller, performing apeer to peer remote copy of the data from the primary storage controllerto the secondary storage controller, wherein in the peer to peer remotecopy an indication is provided to the host that the write command issuccessfully executed without comparing the data stored in the auxiliarystorage of the primary storage controller to the data stored in theauxiliary storage of the secondary storage controller to determinewhether the write command is successfully executed as in the secure peerto peer remote copy operations.
 7. The system of claim 6, wherein theperforming further comprises: in response to determining that the datastaged to the local storage of the primary storage controller isidentical to the data received from the secondary storage controller,sending an indication to the host that the write command is successfullyexecuted.
 8. The system of claim 6, wherein the comparing of the datastored in the auxiliary storage of the primary storage controller to theauxiliary storage of the secondary storage controller to determinewhether the write command is successfully executed is performed atpredetermined intervals of time.
 9. The system of claim 6, wherein: thelocal storage of the primary storage controller is coupled via a bus ofthe primary storage controller to a processor of the primary storagecontroller, and the auxiliary storage of the primary storage controlleris external to an enclosure of the primary storage controller; and thelocal storage of the secondary storage controller is coupled via a busof the secondary storage controller to a processor of the secondarystorage controller and the auxiliary storage of the secondary storagecontroller is external to an enclosure of the secondary storagecontroller.
 10. The system of claim 6, wherein in the normal peer remotecopy operations, in response to an erroneous copy of the data beingstored in the auxiliary storage of the secondary storage controller, thecopy of the data stored in the secondary storage controller cannot beused to correctly replace the data stored in the primary storagecontroller.
 11. A computer program product, the computer program productcomprising a computer readable storage medium having computer readableprogram code embodied therewith, the computer readable program codeconfigured to perform operations, the operations comprising: receiving,by a primary storage controller, a transaction to perform a writecommand from a host, to write data that is to be controlled by theprimary storage controller; in response to determining that a user hasrequested that secure peer to peer remote copy operations are to beperformed between the primary storage controller and a secondary storagecontroller, performing secure peer to peer remote copy operationscomprising: writing the data to a local storage of the primary storagecontroller and subsequently destaging the data from the local storage ofthe primary storage controller to store the data in an auxiliary storageof the primary storage controller; transmitting the data to thesecondary storage controller for writing the data to a local storage ofthe secondary storage controller and subsequently destaging the datafrom the local storage of the secondary storage controller to store thedata in an auxiliary storage of the secondary storage controller;subsequent to the destaging of the data from the local storage of theprimary storage controller to the auxiliary storage of the primarystorage controller, staging the data from the auxiliary storage of theprimary storage controller to the local storage of the primary storagecontroller; subsequent to the destaging of the data from the localstorage of the secondary storage controller to the auxiliary storage ofthe secondary storage controller, staging the data from the auxiliarystorage of the secondary storage controller to the local storage of thesecondary storage controller, and then transmitting the data staged tothe local storage of the secondary storage controller to the primarystorage controller; and subsequent to the staging of the data to thelocal storage of the primary storage controller and the transmitting ofthe data staged to the local storage of the secondary storage controllerto the primary storage controller, comparing the data staged to thelocal storage of the primary storage controller to the data received atthe primary storage controller from the secondary storage controller todetermine whether the write command is successfully executed; and inresponse to determining that the user has requested that normal peer topeer remote copy operations are to be performed between the primarystorage controller and the secondary storage controller, performing apeer to peer remote copy of the data from the primary storage controllerto the secondary storage controller, wherein in the peer to peer remotecopy an indication is provided to the host that the write command issuccessfully executed without comparing the data stored in the auxiliarystorage of the primary storage controller to the data stored in theauxiliary storage of the secondary storage controller to determinewhether the write command is successfully executed as in the secure peerto peer remote copy operations.
 12. The computer program product ofclaim 11, wherein the performing further comprises: in response todetermining that the data staged to the local storage of the primarystorage controller is identical to the data received from the secondarystorage controller, sending an indication to the host that the writecommand is successfully executed.
 13. The computer program product ofclaim 11, wherein the comparing of the data staged to the local storageof the primary storage controller to the data received from thesecondary storage controller is performed at predetermined intervals oftime.
 14. The computer program product of claim 11, wherein: the localstorage of the primary storage controller is coupled via a bus of theprimary storage controller to a processor of the primary storagecontroller, and the auxiliary storage of the primary storage controlleris external to an enclosure of the primary storage controller; and thelocal storage of the secondary storage controller is coupled via a busof the secondary storage controller to a processor of the secondarystorage controller and the auxiliary storage of the secondary storagecontroller is external to an enclosure of the secondary storagecontroller.
 15. The computer program product of claim 11, wherein in thenormal peer remote copy operations, in response to an erroneous copy ofthe data being stored in the auxiliary storage of the secondary storagecontroller, the copy of the data stored in the secondary storagecontroller cannot be used to correctly replace the data stored in theprimary storage controller.